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Updated: Aug 24, 2026

Cooling an Optically Trapped Ultracold Fermi Gas by Periodical Driving
Published on: March 30, 2017
Anomalous Doppler-effect and polariton-mediated cooling of two-level atoms
Peter Domokos1, András Vukics, Helmut Ritsch
1Research Institute for Solid State Physics and Optics, P. O. Box 49, H-1525 Budapest, Hungary.
Abstract:
We consider an atom moving in a near resonant laser field with its dipole strongly coupled to a resonator field mode. As compared to the standard Doppler shift, we find a substantially different and counterintuitive linear velocity dependence of the light scattering properties. The mechanical force of the laser field exhibits strong velocity selectivity at a polariton resonance, which gives rise to an enhanced friction force and Doppler cooling even in the directions perpendicular to the resonator axis. This effect allows for sub-Doppler cooling of atoms even with a nondegenerate ground state.
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